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Experimental study on behavior of mortar-aggregate interface after elevated temperatures

Wan WANG, Jianzhuang XIAO, Shiying XU, Chunhui WANG

《结构与土木工程前沿（英文）》 2017年 第11卷 第2期   页码 158-168 doi: 10.1007/s11709-016-0374-6

摘要： A push-out test program was designed and conducted to study the meso-scale behavior of mortar-aggregate interface for concrete after elevated temperatures ranging from 20°C to 600°C with the concept of modeled concrete (MC) and modeled recycled aggregate concrete (MRAC). The MCs and MRACs were designed with different strength grade of mortar and were exposed to different elevated temperatures. Following that the specimens were cooled to room temperature and push-out tests were conducted. Failure process and mechanical behaviors were analyzed based on failure modes, residual load-displacement curves, residual peak loads and peak displacements. It is found that failure modes significantly depended on specimen type, the elevated temperature and the strength grade of mortar. For MC, major cracks started to propagate along the initial cracks caused by elevated temperatures at about 80% of residual peak load. For MRAC, the cracks appeared at a lower level of load with the increasing elevated temperatures. The cracks connected with each other, formed a failure face and the specimens were split into several parts suddenly when reaching the residual peak load. Residual load-displacement curves of different specimens had similarities in shape. Besides, effect of temperatures and strength grade of mortar on residual peak load and peak displacement were analyzed. For MC and MRAC with higher strength of new hardened mortar, the residual peak load kept constant when the temperature is lower than 400°C and dropped by 43.5% on average at 600°C. For MRAC with lower strength of new hardened mortar, the residual peak load began to reduce when the temperatures exceeded 200°C and reduced by 27.4% and 60.8% respectively at 400°C and 600°C. The properties of recycled aggregate concrete (RAC) may be more sensitive to elevated temperatures than those of natural aggregate concrete (NAC) due to the fact that the interfacial properties of RAC are lower than those of NAC, and are deteriorated at lower temperatures.

关键词： mortar-aggregate interface     push-out test     elevated temperatures     modeled concrete (MC)     modeled recycled aggregate concrete (MRAC)    

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基于简化LSCMA算法的STBC MC－CDMA系统盲多用户检测

熊亦兰,酆广增

《中国工程科学》 2007年 第9卷 第5期   页码 42-45

摘要：

在空时分组编码（STBC）的MC－CDMA系统中，根据STBC正交编码的特点，提出了一种简单可行 的基于常模（CM）准则的盲多用户检测算法

关键词： 盲多用户检测     简化LSCMA算法     空时编码MC-CDMA    

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Comparison of different algicides on growth of

Naiyu Wang, Kai Wang, Can Wang

《环境科学与工程前沿（英文）》 2017年 第11卷 第6期 doi: 10.1007/s11783-017-0940-8

摘要： Eutrophication with a large number of commonly occurs worldwide, thereby threatening the aquatic ecosystem and human health. In this study, four kinds of algicides were tested to explore their influence on cell density and chlorophyll-a of . Results showed that aluminum silicate agent, which inhibited more than 90% cell growth compared with the control group, demonstrated the strongest inhibition effect immediately on growth. Furthermore, the production and release of microcystin (MC)-LR were investigated. Aluminum silicate, CuSO , and Emma-11 were more effective than pyrogallic acid in disrupting the cells of , thereby increasing the extracellular MC-LR concentration. Aluminum silicate caused the highest extracellular MC-LR concentration of more than 45 mg·L . Biotoxicity was also detected to evaluate the environmental risks of MC-LR release, which were related to the usages of different algicides. Extracellular MC-LR concentration mostly increased when the biotoxicity of algae solution increased. The experiments were also designed to reveal the effects of physical conditions in riverways, such as natural sunlight, aeration and benthal sludge, on MC-LR degradation. These findings indicated that UV rays in sunlight, which can achieve a MC-LR removal efficiency of more than 15%, played an important role in MC-LR degradation. Among all the physical pathways of MC-LR removal, benthal sludge adsorption presented the optimal efficiency at 20%.

关键词： Microcystis aeruginosa     MC-LR release     Algicides     MC-LR degradation     Biotoxicity    

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Newly-modeled graphene-based ternary nanocomposite for the magnetophotocatalytic reduction of CO2 with

《化学科学与工程前沿（英文）》 2022年 第16卷 第10期   页码 1438-1459 doi: 10.1007/s11705-022-2166-y

摘要： The development of CO2 into hydrocarbon fuels has emerged as a green method that could help mitigate global warning. The novel structured photocatalyst is a promising material for use in a photocatalytic and magneto-electrochemical method that fosters the reduction of CO2 by suppressing the recombination of electron−hole pairs and effectively transferring the electrons to the surface for the chemical reaction of CO2 reduction. In our study, we have developed a novel-structured AgCuZnS2–graphene–TiO2 to analyze its catalytic activity toward the selective evolution of CO2. The selectivity of each nanocomposite substantially enhanced the activity of the AgCuZnS2–graphene–TiO2 ternary nanocomposite due to the successful interaction, and the selectivity of the final product was improved to a value 3 times higher than that of the pure AgCuZnS2 and 2 times higher than those of AgCuZnS2–graphene and AgCuZnS2–TiO2 under ultra-violet (UV)-light (λ = 254 nm) irradiation in the photocatalytic process. The electrochemical CO2 reduction test was also conducted to analyze the efficacy of the AgCuZnS2–graphene–TiO2 when used as a working electrode in laboratory electrochemical cells. The electrochemical process was conducted under different experimental conditions, such as various scan rates (mV·s–1), under UV-light and with a 0.07 T magnetic-core. The evolution of CO2 substantially improved under UV-light (λ = 254 nm) and with 0.07 T magnetic-core treatment; these improvements were attributed to the facts that the UV-light activated the electron-transfer pathway and the magnetic core controlled the pathway of electron-transmission/prevention to protect it from chaotic electron movement. Among all tested nanocomposites, AgCuZnS2–graphene–TiO2 absorbed the CO2 most strongly and showed the best ability to transfer the electron to reduce the CO2 to methanol. We believe that our newly-modeled ternary nanocomposite opens up new opportunities for the evolution of CO2 to methanol through an electrochemical and photocatalytic process.

关键词： ternary nanocomposite     photocatalytic     electrochemical CO2 reduction     UV-light     magnetic core    

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Size effects in two-dimensional layered materials modeled by couple stress elasticity

Wipavee WONGVIBOONSIN, Panos GOURGIOTIS, Chung Nguyen VAN, Suchart LIMKATANYU, Jaroon RUNGAMORNRAT

《结构与土木工程前沿（英文）》 2021年 第15卷 第2期   页码 425-443 doi: 10.1007/s11709-021-0707-y

摘要： In the present study, the effect of material microstructure on the mechanical response of a two-dimensional elastic layer perfectly bonded to a substrate is examined under surface loadings. In the current model, the substrate is treated as an elastic half plane as opposed to a rigid base, and this enables its applications in practical cases when the modulus of the layer (e.g., the coating material) and substrate (e.g., the coated surface) are comparable. The material microstructure is modeled using the generalized continuum theory of couple stress elasticity. The boundary value problems are formulated in terms of the displacement field and solved in an analytical manner via the Fourier transform and stiffness matrix method. The results demonstrate the capability of the present continuum theory to efficiently model the size-dependency of the response of the material when the external and internal length scales are comparable. Furthermore, the results indicated that the material mismatch and substrate stiffness play a crucial role in the predicted elastic field. Specifically, the study also addresses significant discrepancy of the response for the case of a layer resting on a rigid substrate.

关键词： cosserat     layered materials     size effects     microstructure    

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智能天线MC-CDMA系统中空频联合盲多用户检测算法

傅洪亮,酆广增

《中国工程科学》 2006年 第8卷 第2期   页码 34-38

摘要：

提出了智能天线多载波CDMA系统中一种空域和频域联合的盲多用户自适应检测算法，它是将空域波束形成和频域合并检测合二为一，使得检测器在空域和频域两维上同时优化，从而提高了系统的检测性能。对这种空频联合检测算法的误码性能进行了分析,并与先自适应波束形成然后再进行频域合并的分步算法进行了仿真比较，仿真结果表明，提出的空频联合盲多用户自适应检测算法的检测性能优于分步检测算法。

关键词： 智能天线     多载波     CDMA     联合检测    

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A method for quantifying bias in modeled concentrations and source impacts for secondary particulate

Cesunica E. Ivey, Heather A. Holmes, Yongtao Hu, James A. Mulholland, Armistead G. Russell

《环境科学与工程前沿（英文）》 2016年 第10卷 第5期 doi: 10.1007/s11783-016-0866-6

摘要： A method for quantifying source impacts for secondary PM species is derived. The method provides estimates of bias in modeled concentrations. Adjusted concentrations match corresponding observations at monitored locations. Sources impacts on secondary species are estimated over the US for 20 sources. Community Multi-Scale Air Quality (CMAQ) estimates of sulfates, nitrates, ammonium, and organic carbon are highly influenced by uncertainties in modeled secondary formation processes, such as chemical mechanisms, volatilization, and condensation rates. These compounds constitute the majority of PM mass, and reducing bias in estimated concentrations has benefits for policy measures and epidemiological studies. In this work, a method for adjusting source impacts on secondary species is developed that provides estimates of source contributions and reduces bias in modeled concentrations compared to observations. The bias correction adjusts concentrations and source impacts based on the difference between modeled concentrations and observations while taking into account uncertainties at the location of interest; and it is applied both spatially and temporally. We apply the method over the US for 2006. The mean bias for initial CMAQ concentrations compared to observations is −0.28 (OC), 0.11 (NO ), 0.05 (NH ), and −0.08 (SO ). The normalized mean bias in modeled concentrations compared to observations was effectively zero for OC, NO , NH , and SO after applying the secondary bias correction. 10-fold cross-validation was conducted to determine the performance of the spatial application of the bias correction. Cross-validation performance was favorable; correlation coefficients were greater than 0.69 for all species when comparing observations and concentrations based on kriged correction factors. The methods presented here address model uncertainties by improving simulated concentrations and source impacts of secondary particulate matter through data assimilation. Secondary-adjusted concentrations and source impacts from 20 emissions sources are generated for 2006 over continental US.

关键词： Particulate matter     Source apportionment     Secondary particulate matter     Chemical transport modeling     Receptor modeling    

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Modified condition/decision coverage (MC/DC) oriented compiler optimization for symbolic execution

Wei-jiang Hong, Yi-jun Liu, Zhen-bang Chen, Wei Dong, Ji Wang,zbchen@nudt.edu.cn,wdong@nudt.edu.cn,wj@nudt.edu.cn

《信息与电子工程前沿（英文）》 2020年 第21卷 第9期   页码 1267-1412 doi: 10.1631/FITEE.1900213

摘要： is an effective way of systematically exploring the search space of a program, and is often used for automatic software testing and bug finding. The program to be analyzed is usually compiled into a binary or an intermediate representation, on which is carried out. During this process, s influence the effectiveness and efficiency of . However, to the best of our knowledge, there exists no work on recommendation for with respect to (w.r.t.) , which is an important testing coverage criterion widely used for mission-critical software. This study describes our use of a state-of-the-art tool to carry out extensive experiments to study the impact of s on w.r.t. MC/DC. The results indicate that instruction combining (IC) optimization is the important and dominant optimization for w.r.t MC/DC. We designed and implemented a support vector machine based method w.r.t. IC (denoted as auto). The experiments on two standard benchmarks (Coreutils and NECLA) showed that auto achieves the best MC/DC on 67.47% of Coreutils programs and 78.26% of NECLA programs.
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Microcystin-LR biodegradation by

Chengbin XIAO, Hai YAN, Junfeng WANG, Wei WEI, Jun NING, Gang PAN

《环境科学与工程前沿（英文）》 2011年 第5卷 第4期   页码 526-532 doi: 10.1007/s11783-010-0261-7

摘要： A promising bacterial strain for biodegrading microcystin-LR (MC-LR) as the sole carbon and nitrogen source was successfully isolated from Lake Dianchi, China. The strain was identified as sp. USTB-05, which was the first isolated MCs-biodegrading sp. in China. The average biodegradation rate of MC-LR by sp. USTB-05 was 28.8 mg·L per day, which was apparently higher than those of other bacteria reported so far. The optimal temperature and pH for both strain USTB-05 growth and MC-LR biodegradation were 30°C and 7.0, respectively. The release of MC-LR from the cyanobacterial cells collected from Lake Guishui and the biodegradation of MC-LR by both strain and cell-free extract (CE) were investigated. The results indicated that MC-LR with the initial concentration of 4.0 mg·L in water was biodegraded by sp. USTB-05 within 4 d, while MC-LR with the initial concentration of 28.8 mg·L could be completely removed in 3 h by CE of sp. USTB-05 containing 350 mg·L protein. During enzymatic biodegradation of MC-LR, two intermediate metabolites and a dead-end product were observed on an HPLC chromatogram. Moreover, the similar scanning profiles of MC-LR and its metabolic products indicate that the Adda side-chain of MC-LR was kept intact in all products.

关键词： microcystin-LR(MC-LR)     biodegradation     Sphingopyxis sp     USTB-05     cell-free extract    

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Slender reinforced concrete shear walls with high-strength concrete boundary elements

《结构与土木工程前沿（英文）》 2023年 第17卷 第1期   页码 138-151 doi: 10.1007/s11709-022-0897-y

摘要： Reinforced concrete structural walls are commonly used for resisting lateral forces in buildings. Owing to the advancements in the field of concrete materials over the past few decades, concrete mixes of high compressive strength, commonly referred to as high-strength concrete (HSC), have been developed. In this study, the effects of strategic placement of HSC on the performance of slender walls were examined. The finite-element model of a conventional normal-strength concrete (NSC) prototype wall was validated using test data available in extant studies. HSC was incorporated in the boundary elements of the wall to compare its performance with that of the conventional wall at different axial loads. Potential reductions in the reinforcement area and size of the boundary elements were investigated. The HSC wall exhibited improved strength and stiffness, and thereby, allowed reduction in the longitudinal reinforcement area and size of the boundary elements for the same strength of the conventional wall. Cold joints resulting from dissimilar concrete pours in the web and boundary elements of the HSC wall were modeled and their impact on behavior of the wall was examined.

关键词： slender walls     high-strength concrete     rectangular and barbell-shaped walls     cold joints    

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Stability of three-dimensional printable foam concrete as function of surfactant characteristics

《结构与土木工程前沿（英文）》   页码 935-947 doi: 10.1007/s11709-023-0964-z

摘要： Extrudability is one of the most critical factors when designing three-dimensional printable foam concrete. The extrusion process likely affects the foam stability which necessitates the investigation into surfactant properties particularly for concrete mixes with high foam contents. Although many studies have been conducted on traditional foam concrete in this context, studies on three-dimensional printed foam concrete are scarce. To address this research gap, the effects of surfactant characteristics on the stability, extrudability, and buildability of three-dimensional printed foam concrete mixes with two design densities (1000 and 1300 kg/m3) using two different surfactants and stabilizers (synthetic-based sodium lauryl sulfate stabilized with carboxymethyl cellulose sodium salt, and natural-based hingot surfactant stabilized with xanthan gum) were investigated in this study. Fresh density tests were conducted before and after the extrusion to determine stability of the foam concrete. The results were then correlated with surfactant qualities, such as viscosity and surface tension, to understand the importance of key parameters in three-dimensional printing of foam concrete. Based on the experimental results, surfactant solu1tion with viscosity exceeding 5 mPa·s and surface tension lower than 31 mN/m was recommended to yield stable three-dimensional printable foam concrete mixes. Nevertheless, the volume of foam in the mix significantly affected the printability characteristics. Unlike traditional foam concrete, the variation in the stabilizer concentration and density of concrete were found to have insignificant effect on the fresh-state-characteristics (slump, slump flow, and static yield stress) and air void microstructure of the stable mixes.

关键词： foam concrete     3D printable concrete     stability     rheology     air void microstructure    

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Confinement properties of circular concrete columns wrapped with prefabricated textile-reinforced fineconcrete shells

《结构与土木工程前沿（英文）》 doi: 10.1007/s11709-023-0955-0

摘要： This paper proposes an innovative column composed of a core column (including both reinforced concrete (RC) and plain concrete (PC) columns) and a prefabricated textile-reinforced fine concrete (TRC) shell. To study the confinement properties of TRC shells on this novel type of concrete column, 20 circular specimens, including 12 PC columns and 8 RC columns, were prepared for axial compressive tests. Four key parameters, including the column size, reinforcing ratio of the carbon textile, concrete strength, and stirrup spacing, were evaluated. The results indicated that the compressive properties of the columns were improved by increasing the reinforcing ratio of the textile layers. In the case of TRC-confined PC columns, the maximum improvement in the peak load was 56.3%, and for TRC-confined RC columns, the maximum improvement was 60.2%. Based on the test results, an analytical model that can be used to calculate the stress–strain curves of prefabricated TRC shell-confined concrete columns has been proposed. The calculated curves predicted by the proposed model agreed well with the test results.

关键词： textile-reinforced fine concrete     prefabricated shell     confined concrete column     confinement properties     stress–strain relationship    

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Computational modeling of fracture in concrete: A review

Luthfi Muhammad Mauludin, Chahmi Oucif

《结构与土木工程前沿（英文）》 2020年 第14卷 第3期   页码 586-598 doi: 10.1007/s11709-020-0573-z

摘要： This paper presents a review of fracture modeling of concrete. The complex material, such as concrete, has been widely used in construction industries and become trending issue in the last decades. Based on comprehensive literature review, there are two main approaches considered to-date of concrete fracture modeling, such as macroscopic and micromechanical models. The purpose of this review is to provide insight comparison from different techniques in modeling of fracture in concrete which are available. In the first section, an overview of fracture modeling in general is highlighted. Two different approaches both of macroscopic and micromechanical models will be reviewed. As heterogeneity of concrete material is major concern in micromechanical-based concrete modeling, one section will discuss this approach. Finally, the summary from all of reviewed techniques will be pointed out before the future perspective is given.

关键词： concrete fracture     macroscopic     micromechanical     heterogeneity    

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Experimental study on shear behavior of prestressed reactive powder concrete I-girders

Hui ZHENG, Zhi FANG, Bin CHEN

《结构与土木工程前沿（英文）》 2019年 第13卷 第3期   页码 618-627 doi: 10.1007/s11709-018-0500-8

摘要： As a new generation of concrete, RPC(Reactive Powder Concrete) has attracted great research attention for its ultra-high strength and high durability. In the present paper, experimental results from tests on eight prestressed RPC I-section girders failing in shear are reported herein. The beams with RPC of 120 MPa in compression were designed to assess the ability to carry shear stress in thin webbed prestressed beams with stirrups. The test variables were the level of prestressing, shear span-depth ratio ( / ) and stirrup ratio. Shear deformation, shear capacity and crack pattern were experimentally investigated in detail. With regard to the shear resistance of the test beams, the predictions from three standards (AFGC, JSCE and SIA) on the design of UHPC structures were compared with the experimental result suggesting that the experimental strength is almost always higher than predicted. RPC, as a new concrete, was different from normal concrete and fiber reinforced concrete. Further study should be needed to develop an analytical method and computation model for shear strength of RPC beams.

关键词： prestressed concrete     RPC(Reactive Powder Concrete)     concrete beams     shear strength     experimental study    

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Direct pyrolysis to convert biomass to versatile 3D carbon nanotubes/mesoporous carbon architecture: conversion mechanism and electrochemical performance

《化学科学与工程前沿（英文）》 2023年 第17卷 第6期   页码 679-690 doi: 10.1007/s11705-022-2266-8

摘要： The massive conversion of resourceful biomass to carbon nanomaterials not only opens a new avenue to effective and economical disposal of biomass, but provides a possibility to produce highly valued functionalized carbon-based electrodes for energy storage and conversion systems. In this work, biomass is applied to a facile and scalable one-step pyrolysis method to prepare three-dimensional (3D) carbon nanotubes/mesoporous carbon architecture, which uses transition metal inorganic salts and melamine as initial precursors. The role of each employed component is investigated, and the electrochemical performance of the attained product is explored. Each component and precise regulation of their dosage is proven to be the key to successful conversion of biomass to the desired carbon nanomaterials. Owing to the unique 3D architecture and integration of individual merits of carbon nanotubes and mesoporous carbon, the as-synthesized carbon nanotubes/mesoporous carbon hybrid exhibits versatile application toward lithium-ion batteries and Zn-air batteries. Apparently, a significant guidance on effective conversion of biomass to functionalized carbon nanomaterials can be shown by this work.

关键词： biomass     direct pyrolysis     3D CNTs/MC hybrid     lithium-ion batteries     Zn-air batteries    

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标题 作者 时间 类型 操作

Experimental study on behavior of mortar-aggregate interface after elevated temperatures

Wan WANG, Jianzhuang XIAO, Shiying XU, Chunhui WANG

期刊论文

基于简化LSCMA算法的STBC MC－CDMA系统盲多用户检测

熊亦兰,酆广增

期刊论文

Comparison of different algicides on growth of

Naiyu Wang, Kai Wang, Can Wang

期刊论文

Newly-modeled graphene-based ternary nanocomposite for the magnetophotocatalytic reduction of CO2 with

期刊论文

Size effects in two-dimensional layered materials modeled by couple stress elasticity

Wipavee WONGVIBOONSIN, Panos GOURGIOTIS, Chung Nguyen VAN, Suchart LIMKATANYU, Jaroon RUNGAMORNRAT

期刊论文

智能天线MC-CDMA系统中空频联合盲多用户检测算法

傅洪亮,酆广增

期刊论文

A method for quantifying bias in modeled concentrations and source impacts for secondary particulate

Cesunica E. Ivey, Heather A. Holmes, Yongtao Hu, James A. Mulholland, Armistead G. Russell

期刊论文

Modified condition/decision coverage (MC/DC) oriented compiler optimization for symbolic execution

Wei-jiang Hong, Yi-jun Liu, Zhen-bang Chen, Wei Dong, Ji Wang,zbchen@nudt.edu.cn,wdong@nudt.edu.cn,wj@nudt.edu.cn

期刊论文

Microcystin-LR biodegradation by

Chengbin XIAO, Hai YAN, Junfeng WANG, Wei WEI, Jun NING, Gang PAN

期刊论文

Slender reinforced concrete shear walls with high-strength concrete boundary elements

期刊论文

Stability of three-dimensional printable foam concrete as function of surfactant characteristics

期刊论文

Confinement properties of circular concrete columns wrapped with prefabricated textile-reinforced fineconcrete shells

期刊论文

Computational modeling of fracture in concrete: A review

Luthfi Muhammad Mauludin, Chahmi Oucif

期刊论文

Experimental study on shear behavior of prestressed reactive powder concrete I-girders

Hui ZHENG, Zhi FANG, Bin CHEN

期刊论文

Direct pyrolysis to convert biomass to versatile 3D carbon nanotubes/mesoporous carbon architecture: conversion mechanism and electrochemical performance

期刊论文